Fork lift truck pusher mechanism



Feb. 13, 1962 T.`NAG1N 3,021,024

FORK LIFT TRUCK PusHER MECHANISM Filed April 18, 1960 v s sheets-sheet 1 ulhlllx @fr s L l 'l u TQ NAGIN FORK LIFT TRUCK PUSHER MECHANISM HUMIHUI Feb. 13, 1962 Filed April 18, 1960 Feb. 13, 1962' T.'NAG|N FORK LIFT TRUCK PUSHER MECHANISM 3 Sheets-Sheet .3

Filed April 18, 1960 Mmmm.

United States atent O 3,021,024 FORK LIFT TRUCK PUSLEER MECHANISM Tony Nagin, 14016 S. indiana Ave., Riverdale, Ill. Filed Apr. 18, 1960, Ser. No. 22,866 9 Claims. (Cl. 214-514) The invention relates generally to lift trucks and the like and more particularly to a pusher mechanism therefor.

The present invention is particularly directed to a structure for mechanically pushing articles from the supporting fork structure or the like of a lift truck. At the present time there are a number of devices on the market for performing this operation, most of which employ a scissors type of mechanism for moving the pusher member in operative direction. Such type of structure is quite bulky and has among other disadvantages, the very undesirable characteristic of having the maximum pushing force at substantially the outer end of the travel of the pusher mechanism with minimum power at the beginning of the travel whe-re the power is most needed. Such type of construction embodies a relatively large number of moving parts with corresponding bearing connections, etc.

The present invention therefore has among its objects the production or a pusher mechanism for lift trucks and the like which is exceedingly compact, requiring relatively little if any extra space, and constructed to transmit full uniform power to the pusher structure irrespective of its position along its range of movement.

Another object of the invention is the production of such a pusher mechanism which is extremely simple in construction, employing merely four simple chain pusher 4members and sprocket means, etc. for actuating the same,

the construction being such that it may be readily adapted to and employed on existing structures as well as new equipment.

Many other objects and advantages of the construction herein shown and described will be obvious to those skilled in the art from the disclosure herein given.

In the drawings, wherein like reference characters indicate like or corresponding parts:

FiG. l is a side elevational view of a lift fork structure with portions of the lift mechanism to which it is attached being illustrated in dotted lines;

FIG. 2 is a sectional view taken approximately on the line 2 2 of FIG. l;

FIG. 3 is a sectional view taken approximately on the line 3-3 of FIG. l, with vertical portions ofthe structure broken away;

FIG. 4 is a sectional view taken approximately on the line 4-4 of FIG. 2;

FIG. 5 is a diagrammatic gure of the chain mechanisn and actuating structure therefor;

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FIG. 6 is a perspective view of a link of chain employed in the pusher mechanism;

FIG. 7 is a perspective view similar to FIG. 6 of a modified form of chain structure suitable for use in the Apresent invention; and

FIG. 8 isa diagrammatic ligure similar to FIG. 5 illustrating a modification wherein the' chains are motor actuated. l

The present invention contemplates the use of multiple strand chain, a plurality of pusher chains, which are constructed to permit their passing over actuating sprockets, the chain freely flexing in a direction to permit such action, but beingrelatively rigid in the opposite `direction as Well as under compression. In the embodiment of the inventionillustrated, four such chains are employed, one adjacent each corner of the pusher structure, the chains being retracted or extended, and thus with it the pusher structure, by theoperation of sprocket means which is illustrated as being under the control of a hydraulic cylinder, motor, or the like. When the pusher structure is ICC fully retracted adjacent the lift or elevator structure, the excess chain may be stored in a vertical position, the free ends of the lower chains extending upwardly in a generally vertical plane and the corresponding free ends of the upper chains extending downwardly into such a plane, guide means being provided for such free chain ends. The sprocket means for Iactuating the chains is suitably operated, as for example, by a chain drive operatively connected to a hydraulic cylinder, or motor, whereby movement of the chain will rotate the sprocket means in a di rection to either advance or retract all chains.

Referring to the drawings and more particularly to FIGS. 1, 2 and 3, the reference numeral 1 indicates generally a fork lift structure adapted to be operatively supported through a suitable lift truck elevator support structure, indicated generally by the reference numeral 2 and illustrated in dotted lines in FIG. l.

The lift fork structure 1, as illustrated in FIG. 2, comprises a pair of vertically extending channel members 3 which are operatively connected at their upper ends by a channel member 4 and at their lower ends by a base plate 5, the latter in turn carrying a plurality of fork tines indicated generally by the reference numenal 6 and having horizontally extending portions 7 which terminate at their free ends in beveled or chamfered portions 8, their opposite ends being bent at right angles as indicated at 9, the various elements thus far described being suitably secured together, as for example, by welding to one another or the like.

The structure thus far described may be readily connected to the lift truck through the support structure 2 and elevator structure 2 illustrated in dotted lines, the latter being illustrated as having a pair of members 10 connected through rollers 11 to the support structure 2 for vertical movement relative to the latter, the members 1'0 being retained at the upper end of the plate 5 by a guide channel 12 and at the lower end of the plate 5 by a similar channel 13, whereby the fork structure 1 may be shifted laterally with respect to the members 10. As illustrated in FIG. 2, the movement of the fork structure relative to elevator structure 2 may be controlled by a hydraulic cylinder 14, having the free end of its piston rod 15 operatively connected by a bracket 16 to the base plate 5, the opposite end of the cylinder being operatively connected through a bracket 17 to the elevator 2. Thus by actuation of the cylinder 14 a predetermined amount of lateral movement may be given to the fork lift which lis advantageous in connection with the alignment ofA the forks with the object to be picked up.

As illustrated in FIGS. l and 3, the pusher structure indicated generally by the numeral 18 is generally rectangular in shape, having an outer frame structure 19 comprising top and bottom members 21 and 22 connected by side members 23 and 24, the members being illustrated as formed from rectangularly shaped stock and suitably secured at their free ends, as for example, by welding. Connecting the top and bottom members 21 and 22 are a plurality of cross members 25 illustrated as being formed from T-shaped stock, the cross portion of the T being positioned at the forward or article engaging side of the pusher structure.

structure.

The pusher actuating mechanism If desired, reinforcing angle plates 26 t may be provided adjacent the lower corners of theV 3 illustrated in FIG. 6, each link comprising a pair of side members 29 connected by a pair of rollers 31, only one of which is shown in connection with each link. Respective links are operatively connected by side plate members 32 which are generally rectangular in shape, having parallel top and bottom edges 33 and 34, respectively, and parallel side edges 35, the lower corners of eac'n plate being cut on the diagonal as indicated at 36. Thus in the construction illustrated, the diagonally extending corner portions 36 permit the chain to be curved, as for example, about a sprocket which is positioned below the chain as viewed in FIG. 6, so that the diagonal edges 36 are adjacent the sprocket. However, the square corners formed by the top edge 32 and the side edges 35 of adjacent plates 32 will prevent the chain from being flexed or curved in the opposite direction (upwardly as viewed in FIG. 6), such corner portions engaging one another and maintaining the chain in a substantially straight line unless the same is ilexed in the opposite direction, which would be downwardly as viewed in v FIG. 6.

The chain illustrated in FIG. 7 is generally similar to that illustrated in FIG. 6 and provides a similar interlocking action, the shape of the side plates 32', however, being more diamond-shaped than rectangular, each plate having a triangularly shaped tooth portion 37, the latter on one side of the chain extending in one longitudinal direction and the other extending in the opposite direction as will be apparent from FIG. 7. The opposite edge of each plate 32 is provided with au inclined edge 38 which is complemental to the bottom edge 39 of the portion 37. In the assembled chain each tooth 37 overlies the adjacent inclined edge of the next plate, such interlocking preventing flexing of the ends of the chain upwardly as viewed in FIG. 7b\ pt permitting the chain to be readily curved around a sprocket which would be positioned below the chain as viewed in FIG. 7. Obviously in either of the constructions illustrated in FIGS. 6 and 7, if the chain is prevented from flexing in the one direction, the chain may be readily utilized for the application of compression forces to an element or object.

This chain construction is made use of in the invent1on as the alternating connections between the power source and the pusher structure 18, the chains 27K and 27L being supported on sprockets 40 mounted on a shaft 41,

while chains 28K and 28L are supported on sprockets 42,

cach of which is mounted on a shaft 43.

It will be noted, referring to FIG. l, that the invention is illustrated in connection with a chain such as that illustrated in FIG. 6, the chains 27 and 2S having the diagonally extending edges facing each other whereby the chains may readily pass around their respective sprockets 40 and 42. As illustrated in FIGS. l and 2, t'ne shaft 41 is supported at its opposite end in bearing members 44 which are carried by the channels 3 through suitable plates 45, the latter being secured to the channel by suitable means such as welding and the bearings being illustrated as secured to the respective plates by bolts 46.

In like manner the shafts 43 are carried at their ends adjacent the channel members 3 by bearing members 47 which are operatively connected to the channel members 3 by means of a plate 4S or the like suitably secured to the channel member, as for example, by welding, and the bearing members 47 are operatively secured in position by suitable means such as bolts 46 or the like. The opposite ends of the shaft 43 are illustrated as carried in bearing blocks 49 carried by channel members 51 which are suitably connected, as for example, by Welding to the cross member 4. The intermediate portions of the shaft 41 may likewise be supported by suitable bearing members 52 carried by channel members 53 which are secured at their adjacent ends to the base plate by suitable means such as welding, suitable reinforcing or bracing plates 54 being provided if desired and welded along their adjacent edges to the channels 53 and the base plate 5.

Mounted on shaft 41 are a pair of sprockets 55 and mounted on the inner end of each shaft 43 is a similar sprocket 55, each of the sprockets 55 on the shaft 41 being aligned with a respective sprocket 55 on the corresponding shaft 43 and operatively connected to the aligned pairs of sprockets are roller chains 56. Referring to FIGS. l, 2 and 5, it will be noted that the free ends of the chains are connected to a generally H-shaped member 57, each chain being crossed, with the vertically extending ends of the chain being secured to vertically extending portions 58 of the member 57.

As clearly illustrated in FIGS. 2 and 5, the portions 58 of the member 57 are connected by a cross portion 59, the intermediate portion of each chain extending through elongated vertically extending openings 61 in the members 58. As will be apparent from a reference to FIG. 5, downward movement of the member 57 will result in movement of the chains 56 and rotation of the shafts 41 and 43, shaft 41 and sprockets 40 being rotated in a clockwise direction as viewed in FIG. l, while the shafts 43 and sprockets 42 will be rotated in a counterclockwise direction, thus moving the chains 27 and 28 to the left as viewed in FIG. l.

As illustrated in FIGS. l and 3, the outer ends of the chains 27 are secured to blocks 62 secured to the corner plates 26 and the chains 2S are secured by means of blocks 36 which are secured to plates 64 suitably secured to the pusher structure, as for example, by welding.

As will be apparent from a reference to FIGS. l, 2 and 3, the chains 27K and 27L are adapted to ride upon guide members 6' which are of the same size and shape as the tines 6 and of a transverse width to freely receive and guide the chains. Thus as the chains 27 and 28 are extended, such movement will actuate the pusher structure 19 to move any article resting on the tines 6. As the chains 28 are in a position which will not permit downward flexing of the chain between the sprockets 42 and the pusher mechanism 19, and as such chains will have primarily a guiding action of the upper end of the pusher structure 19 no guide structure is required there- The member 57 may be actuated by suitable means, as for example, as illustrated in FIGS. l and 2, by means of a hydraulic cylinder indicated generally by the numeral 65, illustrated as being connected adjacent its upper end to the cross member 4 by means of a pair of angle plates 66 suitably secured to the cross member 4 by welding or the like, the free end of the piston rod 67 of the cylinder 65 being connected through suitable means such as a clevis 63 to the upstanding portion 69 of the cross portion 59 of the member 57. Thus upon extension of the piston rod 67, and downward movement of the member 57, the pusher structure 19 will be extended outwardly toward the end of the tines 6, whereas upon opposite movement of the member 57 the pusher structure will be retracted to a position adjacent the channel members 3.

Referring to FIGS. 2 and 4, provision is made for storing the chain when the pusher structure is completely retracted, such structure comprising a guide member 71 for each chain, the guide member extending upwardly between the base plate 5 and the channel member 4 and secured to the same. As will be apparent from a reference to FIG. 1, the guide member 71 associated with the chains 27 w1ll extend to the upper end of the associated guide member 6' which is welded to the base plate 5, while the upper end of each member 71 associated with the chains 28 will be positioned adjacent the sprocket 42 associated therewith in a position to receive the associated chain 28L or 28K and guide the same. As illustrated in FIGS. 2 and 4, each pair of adjacent guide members 71 and chains Yassociated therewith are enclosed by cover members 72 as for example, by welding or the like, the cover members being operative to enclose and protect the chains as well Aas prevent the chains from running off of their guide members 71. Likewise to insure retention of the chains 28 on their sprockets 4Z generally triangularly shaped guide members 73 may be mounted on the channel members 4 and adapted to overlie the portions of the chains 28L and ZSR engaged with the sprockets 42, thereby preventing a possible buckle of the chains and disconnection vthereof with their associated roller.

General operation In use, the pusher structure 18 will normally be in a retracted position adjacent the channels 3, in which case the member 57 will be at the end of its upward movement and the piston rod 67 will be fully retracted in the cylinder 65.

Following pickup and transportation of an article or object on the tines 6, such object may be readily pushed Volf of the fork by actuation of the hydraulic cylinder 65 through suitable valve means or the like, thereby causing the piston rod 67 of the cylinder to extend downwardly, carrying with it the member 57 and actuating the chain 56 to rotate the sprockets 42 in a counterclockwise direction and the sprockets 40 in a clockwise direction. This action will result in feeding of the chains 27 and 28 outwardly, moving the pusher structure 18 outwardly to push the object from the fork.

If the operator fails to properly align the fork with the object to be picked up or at the point at which the object is to be dropped, the operator actuates the double acting cylinder 14 iu the proper direction to shift the fork accordingly.

In some cases it may be desirable to provide the pusher ymember with a gripper assembly which could of course be hydraulically or otherwise actuated and it will be noted that the present invention with only four chains connect- 'ing the pusher structure provides adequate space for mounting any other necessary or desirable gripper structures or the like.

FIGURE 8 illustrates a modified form of actuating mechanism for the pusher chains, embodying a suitable hydraulically actuated motor in place of the hydraulic cylinder 65 previously described.

In this construction the sprockets 42 are carried on a single shaft 43', both shafts 41 and 43 being operatively connected through respective worm drive assemblies indicated generally by the numeral 78, each comprising a worm wheel 79 and a cooperable worm 81, suitably journaled in a housing 82. The worrns 81 are operatively connected to a common shaft 83, illustrated as being an extended drive shaft of a hydraulically actuated reversible motor 84 having fluid lines 8 5 and 86 connected thereto, which form the uid supply and return lines.

The motor 84 may be suitably supported from the lift fork structure, as for example, from the channel members 3, by means of a suitable supporting member 87, illustrated as being channel-shaped, on which the rnotor 84 is operatively mounted, with the ends of the member 87 suitably connected to the respective members 3.

The action of thevworms are reversed so that upon rotation of the shaft 43 in a given direction, the shafts 41 and 43' will rotate in their opposite directions to move all chains in a common direction, the particular direction of movement being controlled by the direction of fluid flow into the motor 84. 'Ihe operation otherwise is substantially the same as that previously described.

The motor construction has the advantage of placing substantially no requirements or limitations onthe height of the pusher actuating structure. Obviously Where a relatively long travel is required of the pusher structure, that illustrated in FIGS. l through 4 being suitable for a 48" travel of the pusher structure, a relatively high structure results from the necessary movement of the pisent of the actuating mechanism as the spacing of the shafts 41 and 43 is not critical. This is of particular advantage where the height of the pusher structure is less than that illustrated and the shafts are brought closer to one another.

In some cases, the operating loads may be such that additional strength must be designed into the actuating chains 27 and 28. While larger chains may be employed in some cases, in others the increase in sprocket diameters necessary to accommodate the larger chain undesirably increases the bulk of the pusher actuating structure and in such case the smaller chain may be employed in multiple Widths. Such a construction is illustrated in FIG. 8, wherein a portion of a triple strand chain 88 is shown in dotted lines, the multiple strands being produced by adding additional side members and side plate members, rollers etc. all connected bycommon pins or rivets which are of sufficient length to extend through the respective elements. The resulting structure would provide the additional strength Without change in the sprockets, guide elements, etc.

It will be noted from the above description that I have provided a pusher mechanism which is exceedingly simple in construction anl substantially foolproof in operation, employing merely four roller chain structures for the actual pushing actuation, together with simple means for transmitting the force of a hydraulic cylinder, motor or the like to the chains to move the same in the proper direction.

It will also be appreciated that in view of the simplicity of the construction, it may be readilyutilized on current fork lifts and the like without major changes as the invention readily adapts itself to structures of widely varying shapes and sizes.

videntical therewith, thereby extending the width of the bed accordingly. Consequently, while the guide member 6 could take other shapes, I prefer to keep the same in substantially the same shape as the fork tines.

`It will be noted from the above description that the hydraulic cylinder or motor Will provide a constant or uniform pressure whereby the force applied to the chains 27 and 28 is substantially uniform throughout the travel of the pusher structure, there being no leverage peaks or valleys common to scissor type linkage and the like, which, in structures of the type here involved, provide their maximum leverage as the pusher member approaches its outward limit and its minimum at the initiation of the pushing action. Obviously in such cases it is desirable to have the maxmum force, if possible, at the start of a pushing action to overcome inertia of the article, etc., and in the present invention maximum force is available throughout the travel of the pusher structure, such force remaining substantially uniform` throughout the entire travel.

Having thus described my invention, it will be obvious to those skilled in the art that various immaterial modifications may be made in the same without departing from the spirit of my invention; hence I do not wish to be understood as limiting myself to the exact form, constructions, arrangement and combination of parts herein shown and described, or uses mentioned. g

What I claim as new and desire to secure by Letters Patent is:

1. In a pusher mechanism'for lift Atrucks and the like,

the combination of a pusher assembly comprising a pluspaced chain pusher members each having a free endsecured to the upper portion of said pusher structure,`said chain members being constructed to be relatively rigid under compression when the links thereof are disposed in a straight line, upper and lower sprocket means engageable with the respective chain members` for moving the same in the direction of movement of said pusher structure, guide means for said lower chains extending between said sprockets and the pusher structure throughout the range of pusher movement, operative to maintain the pushing section of said chains disposed therebetween in alignment, said upper chain members being self-supporting in a straight line, chain means operatively connecting the upper and lower sprocket means for rotation thereof in directions to move all of said chain members in the same direction, a hydraulic cylinder having its piston rod operatively connected to said chain means for operatively moving the latter to advance or retract said chain members and the pusher structure connected thereto, and vertically extending guide means for the opposite end portions of said chains.

2. A pusher mechanism as defined in claim l wherein said chain members include side plates having cooperable portions operative to maintain the chain members relatively rigid under compression when disposed in a straight line but permitting the chain member to flex around the associated sprocket means.

3. A pusher mechanism as defined in claim 2, wherein said side plates are of generally rectangular shape with diagonally extending corner portions at the sides of said sprocket means, said side plates having abutting end edges operative to maintain the chain member relatively rigid under compression, permitting said chain to iiex around the associated sprocket means.

4. A pusher mechanism as defined in claim 2, wherein said chains are multiple strand.

5. In a pusher mechanism for lift trucks and the like, the combination of a pusher assembly comprising a plurality of horizontally extending fork tines, a base structure from which said fork tines are carried, a pusher structure movable along said tines for pushing articles therefrom, a lower pair and an upper pair of laterally spaced chain pusher members each having a free end secured to said pusher structure, said chain members being constructed to be relatively rigid under compression when the links thereof are disposed in a straight line, socket means engageable with said chain members for moving the same in the direction of movement of said pusher structure, a rst shaft operatively connecting the lower sprockets and a second shaft operatively connecting the upper sprockets, a drive shaft having its ends operatively connected to the respective rst and second shafts by respective gear mechanisms, a hydraulic motor operatively associated with said driving shaft for reversibly rotating the same, and guide means for said lower chains extending between said sprockets and the pusher structure throughout the range of pusher movement, operative to maintain the pushing section of said chains disposed therebetween in alignment.

6. In a pusher mechanism for lift trucks and the like, the combination of a pusher assembly comprising a plurality of horizontally extending fork tines, a base strueture from which said fork tines are carried, a pusher structure movable along said tines for pushing articles therefrom, a first pair of laterally spaced chain pusher members each having a free end secured to the lower portions of said pusher structure, a second pair of laterally spaced chain pusher members each having a free end secured to the upper portion of said pusher structure, said chain members being constructed to lbe relatively rigid under compression when the links thereof are disposed in a straight line, upper and lower sprocket means engageable with the respective chain members for moving the same in the direction of movement of said pusher structure, guide means for said lower chains extending between said sprockets and the pusher structure throughout the range of pusher movement, operative to maintain the pushing section of said chains disposed therebetween in alignment, said upper chain members being self-supporting in a straight line, power means, means operatively connecting said power means to the upper and lower sprocket means for rotation thereof in directions to move all of said chain members in the same direction to advance or retract the latter and the pusher structure connected thereto, and vertically extending guide means for the opposite end portions of said chains.

7. In a pusher mechanism for lift trucks and the like, the combination of a pusher assembly comprising a plurality of horizontally extending fork tines, a base structure from which said fork tines are carried, a pusher structure movable along said tines for pushing articles therefrom, a lower pair and an upper pair of laterally spaced chain pusher members each having a free end secured to said pusher structure, said chain members being constructed to be relatively rigid under compression when the links thereof are disposed in a straight line, sprocket means engageable with said chain members for moving the same in the direction of movement of said pusher structure, a first shaft operatively connecting the lower sprockets and a second shaft operatively connecting the upper sprockets, power means, means operatively connecting said power means to said first and second shafts for reversibly rotating the same, and guide means for said lower chains extending between said sprockets and the pusher structure throughout the range of pusher movement, operative to maintain the pushing section of said chains disposed therebetween in alignment.

8. In a pusher mechanism for lift trucks and the like, the combination of a pusher assembly comprising a plurality of horizontally extending fork tines, a base structure from which said fork tines are carried, a pair of laterally spaced chain members, each having roller elements positioned upon and movable along the top of an associated fork tine, and having side plate elements disposed at each side of such fork tine whereby said pusher member may ride thereon and be guided thereby, said chain members being constructed to be relatively rigid under compression when the links thereof are disposed in a straight line and relatively non-flexing in an upward direction tending to detach the chain members from their associated fork tines, a pusher member connected to and movable with the ends of said chain members adjacent the outer ends of said fork tines, power means, and means operatively connecting said power means to said chain for reversibly moving the same along said fork tines to advance or retract said pusher member.

9. A pusher mechanism as defined in claim 8, wherein said connecting means includes sprocket means engageable with the respective chain members for transmitting movement thereto, said Asprocket means being disposed above said chain members whereby the latter may flex partially around the same.`

References Cited in the file of this patent 

